Tat Tvam Asi (Devanagari: तत्त्वमसि), a Sanskrit phrase, translated variously as "Thou art that," (That thou art, That art thou, You are that, or That you are, or You're it) is one of the Mahāvākyas (Grand Pronouncements) in VedanticSanatana Dharma. It originally occurs in the Chandogya Upanishad 6.8.7,[1] in the dialogue between Uddalaka and his son Śvetaketu; it appears at the end of a section, and is repeated at the end of the subsequent sections as a refrain. The meaning of this saying is that the Self - in its original, pure, primordial state - is wholly or partially identifiable or identical with the Ultimate Reality that is the ground and origin of all phenomena.

The Vedas form the fundamental source text for everything in Hinduism. Each of the four Vedas has metaphysical speculations, known as Upanishads, at the end. Among the various discussions in these Upanishads there are mahavakyas (Grand pronouncements), which are of foundational import and deep significance. Tat tvam asi (meaning, That Thou Art) is one such.[citation needed] This is from Chandogya Upanishad. Different schools of philosophy interpret such fundamental statements in significantly different ways, so as to be consistent with their own philosophical thought. Below is the interpretation of the Vishishtadvaita school.

The argument that AtmA+atat(आत्मा+अतत् ) cannot happen just as brahmaa + ashiraha(ब्रह्मा+अशिरः) cannot is not valid. In the word brahmārpanam (ब्रह्मार्पणम्), it cannot be split as brahma+ rpanam (ब्रह्मा+ र्पणम्), but it can only be brahma+ arpanam (ब्रह्मा+अर्पणम्). One cannot even argue that since rpanam is meaningless, it has to be arpanam. The argument that AtmA+atat(आत्मा+अतत् ) cannot happen is baseless, just as brahma+arpanam (ब्रह्मा+अर्पणम्) cannot happen is also baseless. AtmA+atat(आत्मा+अतत् ) means Atman+atat(आत्मन्+अतत् ).

When Uddalaka is having dialog with his son Shvetaketu, if he is saying “O Atman, that thou art”, what are these words referring to? Since “Atman” is addressing, “thou” must also refer to Atman. If “thou” points to the Supreme inner self, then the statement simply means “O Supreme inner self, you, the Supreme inner self is that, Supreme inner self”. This simply becomes a redundant statement that is trivially true. There are only two ways the triviality can go. One is Atman refers to individual self and that refers to Supreme inner self and negating their selfsameness is the purport. “O Individual self, you are not that Supreme inner self.” The second way is to note that in Vedic grammar, the Nominative case is representative of other cases. In Accusative case sense, it means that the very object and purpose of an Individual self is Supreme self. In Instrumental case it means that the Supreme inner self or the Lord is instrumental for every action of Individual self. In Dative case, it means the very goal of Individual self is to reach the Supreme inner self. In Ablative case, it means the very origin of Individual self is the Supreme Self. It also means that Individual self is eternally dependent on Supreme self. In Genitive case, it means that Individual self does not own anything as everything belongs to Supreme self. The individual self itself belongs to Supreme self. In Locative case it means the Individual self is located in Supreme self and thus always seeking support for the very existence. Thus in every which way, the eternal dependence is indicated.

Now when Shvetaketu completes his studies and comes home and shows his arrogance, that is when his father Uddalaka starts this dialog. His instructions must include something that takes away his arrogance. That being the case, why would the father address the son and tell him that the Individual self of Shvetaketu is same as the Supreme self? No philosopher would equate the dress or the physical body to either the individual self or Supreme self. On the same token, one must not also equate the Individual self with the Supreme self. The Supreme self is not dependent on cosmic Maya to perform His actions like creation nor can He become a victim of avidya(ignorance) that can degenerate Him to the level of Individual self.

Further, the nine examples that are given by Uddalaka to Shvetaketu speak of the differences and dependency and thus removing any scope for interpretation of identity in that statement.